解:(1)375÷(1-50%-20%),
=375÷30%,
=1250(只);
答:養(yǎng)雞、鴨、鵝共1250只.
(2)375-1250×20%,
=375-250,
=125(只);
答:養(yǎng)的鴨比鵝多125只.
(3)1250×50%=625(只);
(625-375)÷375,
=250÷375,
≈66.67%;
答:養(yǎng)雞的只數(shù)比鴨多66.67%.
分析:(1)把養(yǎng)雞鴨鵝的總只數(shù)看成單位“1”,先求出鴨的只數(shù)占總只數(shù)的百分之幾,它對應(yīng)的數(shù)量是375只,由此用除法求出總只數(shù);
(2)用總只數(shù)乘上20%就是鵝的只數(shù),然后用鴨的只數(shù)減去鵝的只數(shù)即可;
(3)用總只數(shù)乘上50%就是雞的只數(shù),先求出雞比鴨多幾只,再用多的只數(shù)除以鴨的只數(shù)即可.
點評:解答此題的關(guān)鍵是根據(jù)對應(yīng)的數(shù)字除以對應(yīng)的百分?jǐn)?shù)可計算出雞鴨鵝的總只數(shù),列式解答即可.